Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
An electrochemical amperometric sensor can measure a concentration of an analyte by measuring a current through a working electrode that is generated by electrochemical oxidation or reduction reactions related to the analyte. A reduction reaction occurs when electrons are transferred from the electrode, whereas an oxidation reaction occurs when electrons are transferred to the electrode. The direction of the electron transfer is dependent upon a voltage applied to the working electrode. At least one other electrode (e.g., a counter electrode, a reference electrode) can complete the circuit. When the working electrode is appropriately biased, the output current can be proportional to the reaction rate, which can provide a measure of the concentration of the analyte surrounding the working electrode.
A potentiostat may be configured to apply a voltage to the working electrode, relative to the reference electrode, and measure the current through the working electrode, such that the current is related to the concentration of the analyte. In some examples, the potentiostat may include an analog-to-digital converter (ADC) that provides a digital output that is representative of the current through the working electrode. In a conventional approach, the input current is integrated by an active integrator to provide a ramp voltage. However, the arrangement of the electrodes in an electrochemical sensor can result in a relatively high capacitance at the input of the active integrator. Operating the active integrator with such high input capacitance may result in high power consumption by the active components.